. >> reporter: he insisted he will lead, not follow, at the pentagon and around the world. >> america must engage in the world. not to retreat from the world. >> reporter: for hours, one republican after another accused the two-term nebraska senator of shading his true believes. among their concerns, past statements criticizing israel. >> do you think that it is right that israel was committing a "sickening slaughter" as you said in the senate? >> name one person in your opinion who is intimidated by the israeli lobby in the united states senate? >> your use of intimidation? i should have used influence. >> reporter: more focus on this area, where he looked at more nuclear weapons, even if the u.s. goes firsts. he says he doesn't agree with all the findings. >> why would you ever put your name on a report that is inconsistent with what you're telling us today? >> reporter: but the big flash point? iran, where he stumbled talking about basic u.s. policy, calling iran a "legitimate government". >> i do not see iran as a legitimate government. i would like your thoughts on that. >> what